This is a tricky one

Mathematics

1 answer:

IgorLugansk [536]3 years ago

3 0

X = 12 , just solved it right now :)

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Find the sum or difference 5/6 + 4/9

Naily [24]

The closest option to the actual answer is a.

1 5/18 is the actual answer.

If you make both the denominators the same, then you can actually add the fractions together.

To make both of the denominators the same, you need to multiply 5/6 by 9 and 4/9 by 6, which would result in 45/54 + 24/54= 69/54 = 23/18. If we convert it to a mixed fraction, it would result into 1 5/18.

6 0

3 years ago

Brewed decaffeinated coffee contains some caffeine. We want to estimate the amount of caffeine in 8 ounce cups of decaf coffee a

rusak2 [61]

Answer:

We would have to take a sample of 62 to achieve this result.

Step-by-step explanation:

Confidence level of 95%.

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

Assume that the standard deviation in the amount of caffeine in 8 ounces of decaf coffee is known to be 2 mg.

This means that $\sigma = 2$

If we wanted to estimate the true mean amount of caffeine in 8 ounce cups of decaf coffee to within /- 0.5 mg, how large a sample would we have to take to achieve this result?

We would need a sample of n.

n is found when $M = 0.5$ . So